Table output - columns order

Question

This is curiosity, I'm not stuck, just wondering... I've never seen this behaviour before and couldn't find the reason...

The code I'm executing works fine but I don't understand why the order of my columns doesn't match the order I'm adding them to my $record...

So I create these :

$result = @()

$record = @{

    "Server" = ""
    "Primary DNS" = ""
    "Secundary DNS" = ""
    "DHCP Enabled" = ""

}

Later I add my values :

$record."Server" = $server
$record."Primary DNS" = $DNS1
$record."Secundary DNS" = $DNS2
$record."DHCP Enabled" = $NetAdapter.DHCPEnabled
$objRecord = New-Object psobject -Property $record
$result += $objRecord

But then the output of $result gives me a table where the columns go "Primary DNS", "DHCP Enabled", "Server", "Secundary DNS".

It's not random... if I don't specify an order myself with Select-Object, the above order is always the one I get.

Thanks in advance for the education (^^,)

Another (possible) learning item: try to avoid using the increase assignment operator (+=) to create an object collection as it is exponential expensive. — iRon
– iRon, Commented Jul 17, 2020 at 12:20
Alright iRon - thanks ! Took me a few trials to figure out how I had to change my code but in the end it was pretty simple. Basically I removed $result = @() and I replaced $result += $objRecord with $objRecord (and now I can either have that output or pipe to Export-CSV or whatever...) Thanks again ! — Michel Balencourt
– Michel Balencourt, Commented Sep 8, 2020 at 13:40

mclayton · Accepted Answer · 2020-07-17 10:45:16Z

3

@{ ... } creates a Hashtable, which doesn't have a defined order for the entries:

PS> $record = @{
  "Server" = ""
  "Primary DNS" = ""
  "Secundary DNS" = ""
  "DHCP Enabled" = ""
}

PS> $record.GetType().FullName
System.Collections.Hashtable

PS> $record
Name                           Value
----                           -----
Primary DNS
DHCP Enabled
Server
Secundary DNS

If you use [ordered] @{ ... } it creates an OrderedDictionary instead, which does maintain the order of entries:

PS> $record = [ordered] @{
  "Server" = ""
  "Primary DNS" = ""
  "Secundary DNS" = ""
  "DHCP Enabled" = ""
}

PS> $record.GetType().FullName
System.Collections.Specialized.OrderedDictionary

PS> $record

Name                           Value
----                           -----
Server
Primary DNS
Secundary DNS
DHCP Enabled

edited Jul 17, 2020 at 10:45

answered Jul 17, 2020 at 9:50

mclayton

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Comments

avarice · Accepted Answer · 2020-07-17 10:05:41Z

1

@mclayton posted an helpful answer regarding ordered list. As we can see, you are adding the values later, then you can use this format:

$record = New-Object PSObject
$record | Add-Member -MemberType NoteProperty -Name Server -Value $server -PassThru | 
Add-Member -MemberType NoteProperty -Name "Primary DNS" -Value $DNS1 -PassThru |
Add-Member -MemberType NoteProperty -Name "Secondary DNS" -Value $DNS2 -PassThru | 
Add-Member -MemberType NoteProperty -Name "DHCP Enabled" -Value $NetAdapter.DHCPEnabled -PassThru
$objRecord = [pscustomobject]$record

answered Jul 17, 2020 at 10:05

avarice

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